It is known that neural networks have the problem of being over-confident when directly using the output label distribution to generate uncertainty measures. Existing methods mainly resolve this issue by retraining the entire model to impose the uncertainty quantification capability so that the learned model can achieve desired performance in accuracy and uncertainty prediction simultaneously. However, training the model from scratch is computationally expensive and may not be feasible in many situations. In this work, we consider a more practical post-hoc uncertainty learning setting, where a well-trained base model is given, and we focus on the uncertainty quantification task at the second stage of training. We propose a novel Bayesian meta-model to augment pre-trained models with better uncertainty quantification abilities, which is effective and computationally efficient. Our proposed method requires no additional training data and is flexible enough to quantify different uncertainties and easily adapt to different application settings, including out-of-domain data detection, misclassification detection, and trustworthy transfer learning. We demonstrate our proposed meta-model approach's flexibility and superior empirical performance on these applications over multiple representative image classification benchmarks.
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In consequential decision-making applications, mitigating unwanted biases in machine learning models that yield systematic disadvantage to members of groups delineated by sensitive attributes such as race and gender is one key intervention to strive for equity. Focusing on demographic parity and equality of opportunity, in this paper we propose an algorithm that improves the fairness of a pre-trained classifier by simply dropping carefully selected training data points. We select instances based on their influence on the fairness metric of interest, computed using an infinitesimal jackknife-based approach. The dropping of training points is done in principle, but in practice does not require the model to be refit. Crucially, we find that such an intervention does not substantially reduce the predictive performance of the model but drastically improves the fairness metric. Through careful experiments, we evaluate the effectiveness of the proposed approach on diverse tasks and find that it consistently improves upon existing alternatives.
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本文研究了在因果图形模型中设计最佳干预措施序列的问题,以最大程度地减少对事后最佳干预的累积后悔。自然,这是一个因果匪徒问题。重点是线性结构方程模型(SEM)和软干预措施的因果匪徒。假定该图的结构是已知的,并且具有$ n $节点。每个节点都假定使用两种线性机制,一种软干预和一种观察性,产生了$ 2^n $可能的干预措施。现有的因果匪徒算法假设,至少完全指定了奖励节点父母的介入分布。但是,有$ 2^n $这样的分布(一个与每个干预措施相对应),即使在中等尺寸的图中也变得越来越高。本文分配了知道这些分布的假设。提出了两种算法,用于常见者(基于UCB)和贝叶斯(基于汤普森采样)的设置。这些算法的关键思想是避免直接估计$ 2^n $奖励分布,而是估算完全指定SEMS($ n $线性)的参数,并使用它们来计算奖励。在这两种算法中,在噪声和参数空间的有界假设下,累积遗憾的是$ \ tilde {\ cal o}(((2d)^l l \ sqrt {t})$,其中$ d $是图的最高度和$ l $是其最长因果路径的长度。
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可靠,高分辨率气候和天气数据的可用性对于为气候适应和缓解的长期决策提供了重要的意见,并指导对极端事件的快速响应。预测模型受到计算成本的限制,因此通常以粗空间分辨率预测数量。统计降尺度可以提供高采样低分辨率数据的有效方法。在这个领域,经常使用计算机视觉中超分辨率域中的方法成功地应用了深度学习。尽管经常取得令人信服的结果,但这种模型在预测物理变量时通常会违反保护法。为了节省重要的物理量,我们开发的方法可以通过深层缩减模型来确保物理约束,同时还根据传统指标提高其性能。我们介绍了约束网络的两种方法:添加到神经网络末尾的重新归一化层,并连续的方法随着增加的采样因子的增加而扩展。我们使用ERE5重新分析数据显示了我们在不同流行架构和更高采样因子上的方法的适用性。
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培训生成模型捕获数据的丰富语义并解释由此类模型编码的潜在表示,这是无监督学习的非常重要的问题。在这项工作中,我们提供了一种简单的算法,该算法依赖于对预训练的生成自动编码器的潜在代码进行扰动实验,以发现生成模型暗示的因果图。我们利用预训练的属性分类器并执行扰动实验,以检查给定潜在变量对属性子集的影响。鉴于此,我们表明人们可以拟合有效的因果图,该图形在被视为外源变量的潜在代码和被视为观察到的变量的属性之间建模结构方程模型。一个有趣的方面是,单个潜在变量控制属性的多个重叠子集,与试图实现完全独立性的常规方法不同。使用在肽序列数据集上训练的基于RNN的预先训练的生成自动编码器,我们证明了从各种属性和潜在代码之间的算法中学习的因果图可用于预测看不见的序列的特定属性。我们比较了对所有可用属性训练的预测模型,或者仅在Markov毯子中仅培训的模型,并从经验上表明,在无监督和监督的制度中,通常使用依赖Markov blanket属性的预测变量,以确保更好的分布序列。 。
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本文考虑了从观察和介入数据估算因果导向的非循环图中未知干预目标的问题。重点是线性结构方程模型(SEM)中的软干预。目前对因果结构的方法学习使用已知的干预目标或使用假设测试来发现即使是线性SEM也可以发现未知的干预目标。这严重限制了它们的可扩展性和样本复杂性。本文提出了一种可扩展和高效的算法,始终识别所有干预目标。关键思想是从与观察和介入数据集相关联的精度矩阵之间的差异来估计干预站点。它涉及反复估计不同亚空间子集中的这些站点。该算法的算法还可用于将给定的观察马尔可夫等效类更新为介入马尔可夫等价类。在分析地建立一致性,马尔可夫等效和采样复杂性。最后,实际和合成数据的仿真结果展示了所提出的可扩展因果结构恢复方法的增益。算法的实现和重现仿真结果的代码可用于\ url {https://github.com/bvarici/intervention- istimation}。
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如果对准确的预测的置信度不足,则选择性回归允许弃权。通常,通过允许拒绝选项,人们期望回归模型的性能会以减少覆盖范围的成本(即预测较少的样本)的成本提高。但是,正如我们所显示的,在某些情况下,少数子组的性能可以减少,同时我们减少覆盖范围,因此选择性回归可以放大不同敏感亚组之间的差异。在这些差异的推动下,我们提出了新的公平标准,用于选择性回归,要求每个子组的性能在覆盖范围内降低。我们证明,如果特征表示满足充分性标准或为均值和方差进行校准,则与所提出的公平标准相比。此外,我们介绍了两种方法,以减轻子组之间的性能差异:(a)通过在高斯假设下正规化有条件相互信息的上限,以及(b)通过对条件均值和条件方差预测的对比度损失正规。这些方法的有效性已在合成和现实世界数据集上证明。
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Dense prediction tasks such as segmentation and detection of pathological entities hold crucial clinical value in the digital pathology workflow. However, obtaining dense annotations on large cohorts is usually tedious and expensive. Contrastive learning (CL) is thus often employed to leverage large volumes of unlabeled data to pre-train the backbone network. To boost CL for dense prediction, some studies have proposed variations of dense matching objectives in pre-training. However, our analysis shows that employing existing dense matching strategies on histopathology images enforces invariance among incorrect pairs of dense features and, thus, is imprecise. To address this, we propose a precise location-based matching mechanism that utilizes the overlapping information between geometric transformations to precisely match regions in two augmentations. Extensive experiments on two pretraining datasets (TCGA-BRCA, NCT-CRC-HE) and three downstream datasets (GlaS, CRAG, BCSS) highlight the superiority of our method in semantic and instance segmentation tasks. Our method outperforms previous dense matching methods by up to 7.2 % in average precision for detection and 5.6 % in average precision for instance segmentation tasks. Additionally, by using our matching mechanism in the three popular contrastive learning frameworks, MoCo-v2, VICRegL and ConCL, the average precision in detection is improved by 0.7 % to 5.2 % and the average precision in segmentation is improved by 0.7 % to 4.0 %, demonstrating its generalizability.
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Information overloading requires the need for summarizers to extract salient information from the text. Currently, there is an overload of dialogue data due to the rise of virtual communication platforms. The rise of Covid-19 has led people to rely on online communication platforms like Zoom, Slack, Microsoft Teams, Discord, etc. to conduct their company meetings. Instead of going through the entire meeting transcripts, people can use meeting summarizers to select useful data. Nevertheless, there is a lack of comprehensive surveys in the field of meeting summarizers. In this survey, we aim to cover recent meeting summarization techniques. Our survey offers a general overview of text summarization along with datasets and evaluation metrics for meeting summarization. We also provide the performance of each summarizer on a leaderboard. We conclude our survey with different challenges in this domain and potential research opportunities for future researchers.
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Graph processing applications are severely bottlenecked by memory system performance due to low data reuse and irregular memory accesses. While state-of-the-art prefetchers using Machine Learning (ML) have made great progress, they do not perform well on graph analytics applications due to phase transitions in the execution and irregular data access that is hard to predict. We propose MPGraph: a novel ML-based Prefetcher for Graph analytics. MPGraph makes three novel optimizations based on domain knowledge of graph analytics. It detects the transition of graph processing phases during execution using a novel soft detection technique, predicts memory accesses and pages using phase-specific multi-modality predictors, and prefetches using a novel chain spatio-temporal prefetching strategy. We evaluate our approach using three widely-used graph processing frameworks and a variety of graph datasets. Our approach achieves 34.17%-82.15% higher precision in phase transition detection than the KSWIN and decision tree baselines. Our predictors achieve 6.80%-16.02% higher F1-score for access prediction and 11.68%-15.41% higher accuracy-at-10 for page prediction compared with the baselines LSTM-based and vanilla attention-based models. Simulations show that MPGraph achieves on the average 87.16% (prefetch accuracy) and 73.29% (prefetch coverage), leading to 12.52%-21.23% IPC improvement. It outperforms the widely-used non-ML prefetcher BO by 7.58%-12.03%, and outperforms state-of-the-art ML-based prefetchers Voyager by 3.27%-4.42% and TransFetch by 3.73%-4.58% with respect to IPC improvement.
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